partial class Examples
{
  public static Result FilletCurves(RhinoDoc doc)
  {
    var gc1 = new GetObject();
    gc1.DisablePreSelect();
    gc1.SetCommandPrompt("Select first curve to fillet (close to the end you want to fillet)");
    gc1.GeometryFilter = ObjectType.Curve;
    gc1.GeometryAttributeFilter = GeometryAttributeFilter.OpenCurve;
    gc1.Get();
    if (gc1.CommandResult() != Result.Success)
      return gc1.CommandResult();
    var curve1_obj_ref = gc1.Object(0);
    var curve1 = curve1_obj_ref.Curve();
    if (curve1 == null) return Result.Failure;
    var curve1_point_near_end = curve1_obj_ref.SelectionPoint();
    if (curve1_point_near_end == Point3d.Unset)
      return Result.Failure;

    var gc2 = new GetObject();
    gc2.DisablePreSelect();
    gc2.SetCommandPrompt("Select second curve to fillet (close to the end you want to fillet)");
    gc2.GeometryFilter = ObjectType.Curve;
    gc2.GeometryAttributeFilter = GeometryAttributeFilter.OpenCurve;
    gc2.Get();
    if (gc2.CommandResult() != Result.Success)
      return gc2.CommandResult();
    var curve2_obj_ref = gc2.Object(0);
    var curve2 = curve2_obj_ref.Curve();
    if (curve2 == null) return Result.Failure;
    var curve2_point_near_end = curve2_obj_ref.SelectionPoint();
    if (curve2_point_near_end == Point3d.Unset)
      return Result.Failure;

    double radius = 0;
    var rc = RhinoGet.GetNumber("fillet radius", false, ref radius);
    if (rc != Result.Success) return rc;

    var join = false;
    var trim = true;
    var arc_extension = true;
    var fillet_curves = Curve.CreateFilletCurves(curve1, curve1_point_near_end, curve2, curve2_point_near_end, radius,
      join, trim, arc_extension, doc.ModelAbsoluteTolerance, doc.ModelAngleToleranceDegrees);
    if (fillet_curves == null /*|| fillet_curves.Length != 3*/)
      return Result.Failure;

    foreach(var fillet_curve in fillet_curves)
      doc.Objects.AddCurve(fillet_curve);
    doc.Views.Redraw();
    return rc;
  }
}
